What's this bird?

[Tyre Smoke]

Looks like a fledgling but very late in the year for that. Flies straight but flaps a lot, not like a woodpecker for example that flaps and gains height then glides. Larger than a blackbird, smaller than a jay.

We live on the edge of Exmoor, open fields and copse of trees, mostly deciduous trees.

[Roofless Toothless]

By the cut of the tail, I'd say a fieldfare.

[Boosted LS1]

Agreed. OP, did it look like a large grey thrush?

[Tyre Smoke]

Yes, but looked more black than grey. I'd say it was slightly bigger than a thrush. But as you can tell, I took the pic on my phone from about 30 feet away and behind glass.